Image monitoring system and image monitoring program

ABSTRACT

An image monitoring system includes: recording means for recording an image captured by a camera via a network; control means for controlling the system so as to display the present image captured by the camera or a past image recorded on the recording means on display means; and moving-object detecting means for detecting a moving object from the image captured by the camera; wherein the moving-object detecting means includes resolution conversion means for generating an image with a resolution lower than the resolution of the image captured by the camera, positional-information output means for detecting a moving object from the image generated by the resolution conversion means and outputting positional information on the detected moving object, and information merging means for merging the positional information of the moving object with the image captured by the camera on the basis of the positional information of the moving object output by the positional-information output means.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2006-059261 filed in the Japanese Patent Office on Mar.6, 2006, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image monitoring system and an imagemonitoring program that can display an image in a camera connected to anetwork and that can record and reproduce the captured image, and inparticular, it relates to an image monitoring system and an imagemonitoring program equipped with the function of detecting a movingobject in the captured image.

2. Background Art

Image monitoring systems are systems that display images captured by aplurality of cameras on a monitor in split views to allow the images tobe watched at one place at the same time and that record the capturedimages and reproduce the past images as necessary. In recent years, suchimage monitoring has been executed, in view of improvement in security,not only inside and outside of banks and shops such as conveniencestores but also in companies, parking lots, streets, schools,apartments, detached houses, and other places.

On the other hand, network-ready image monitoring systems have appearedin which a plurality of cameras is connected to a network so as to allowmanagement of display, storage, and reproduction of images via thenetwork, as image-capture cameras have become sophisticated and fallenin price, recording media have increased in capacity and fallen inprice, and networks have developed.

Such image monitoring systems have the function of detecting a movingobject from images captured by cameras, which is applied to monitoringworks. This moving-object detecting function is used for operations suchas finding a difference in pixel value between the present frame and apreceding frame to detect a moving object according to the value of thedifference or the size of the area where the difference occurs,displaying the position of the moving object on monitors, or recordingan image only when detecting a moving-object (for example, refer toJP-A-9-186988).

SUMMARY OF THE INVENTION

However, such moving-object detecting function uses many CPUs and memoryresources because all the images sent from cameras one by one aresubjected to operations, resulting in application of a heavy load on thesystem. Particularly, with network-ready image monitoring systems towhich a plurality of cameras can be connected, when moving-objectdetection is carried out for all the images sent from the cameras via anetwork, an excessive load will be applied to the systems.

According to an embodiment of the invention, there is provided an imagemonitoring system including: recording means for recording an imagecaptured by a camera via a network; control means for controlling thesystem so as to display the present image captured by the camera or apast image recorded on the recording means on display means; andmoving-object detecting means for detecting a moving object from theimage captured by the camera. The moving-object detecting means includesresolution conversion means for generating an image with a resolutionlower than the resolution of the image captured by the camera,positional-information output means for detecting a moving object fromthe image generated by the resolution conversion means and outputtingpositional information on the detected moving object, and informationmerging means for merging the positional information of the movingobject with the image captured by the camera on the basis of thepositional information of the moving object output by thepositional-information output means.

According to an embodiment of the invention, there is provided an imagemonitoring program executed by the image monitoring system, in which themoving-object detecting means generates an image with a resolution lowerthan the resolution of the image captured by the camera, detects amoving object from the low-resolution image, and merges the positionalinformation of the detected moving object with the image captured by thecamera.

According to an embodiment of the invention, in the process of detectinga moving object from an image by moving-object detecting means, an imagewith a resolution lower than that of the image captured by the camera,and moving-object detection is performed using the low-resolution image.Thus the load of the process of detecting a moving object can bereduced.

Accordingly, in the image monitoring system with a moving-objectdetecting function according to the embodiments of the invention,consumption of system resources for detecting a moving object can bereduced and the overall performance can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the structure of an image monitoringsystem according to an embodiment of the invention;

FIG. 2 is a schematic diagram of the structure of an image monitoringprogram according to an embodiment of the invention;

FIG. 3 is a block diagram of a moving-object detecting section for usein the image monitoring system of the embodiment;

FIG. 4 is a flowchart for a moving-object detection process which is theimage monitoring program of the embodiment; and

FIG. 5 is a diagram of an example of images captured by a plurality ofcameras which are displayed on a monitor.

DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of the invention will be described hereinbelow withreference to the drawings. FIG. 1 is a schematic diagram of thestructure of an image monitoring system according to the embodiment; andFIG. 2 is a schematic diagram of the structure of an image monitoringprogram according to the embodiment.

As shown in FIG. 1, the image monitoring system according to theembodiment includes a camera 10 (or more) connected to a network N, amonitoring device 20 connected to the network N, and a monitor (displaymeans) 30 connected to the monitoring device 20. The image monitoringsystem sends an image captured by the camera 10 to the monitoring device20 in a specified data format (for example, Joint Photographic ExpertsGroup (JPEG) or Moving Picture Experts Group phase 4 (MPEG-4) via thenetwork N to allow the present image to be displayed on the monitor 30connected to the monitoring device 20, and the sent image to be recordedon a hard disk drive (HDD) 23 which is recording means provided in themonitoring device 20. The image monitoring system also allows a pastimage recorded on the HDD 23 to be searched for and reproduced.

To manage the images sent from the camera 10 via the network N, themonitoring device 20 includes a CPU 21 serving as control means thatexecutes an image monitoring program, a memory 22 such as a randomaccess memory (RAM) for use as a work area in image processing etc., andthe HDD 23 serving as the recording means in which images sent from thecamera 10 are stored one after another. The monitoring device 20 alsoincludes a monitor interface 24 for connecting the monitor 30, anexternal unit interface 25 for connecting external units including ajoystick and an add-on HDD, and a network interface 26 for inputting andoutputting to/from the network N.

As shown in FIG. 2, the image monitoring program executed by the CPU 21includes a record server 101 executed on an operating system 100 and agraphical user interface (GUI) controller 102. The record server 101manages the images sent from the camera 10 together with a cameraidentification number, record date, and compression format, and recordsthem on the HDD 23 to create an image database. The record server 101also searches the HDD 23 for a past image and reproduces it according tothe instruction of the user.

The GUI controller 102 controls the window of the monitor 30 (seeFIG. 1) for displaying images thereon, assignment of the images on thewindow, the display of various control buttons (icons) on the window,and acceptance of instructions from the user with input means such as amouse, a keyboard, function buttons, or a joystick.

With the system configuration and program configuration, an imagecaptured by the camera 10 is sent to the monitoring device 20 via thenetwork N and displayed on the monitor 30. When a plurality of cameras10 is connected, images captured by the cameras 10 are displayed on therespective windows of the monitor 30, or only a window for a specificcamera 10 is displayed on the entire screen of the monitor 30. When thecamera 10 has a pan/tilt/zoom function, an image can be displayedthrough the pan/tilt/zoom of the camera 10 by the control of the user.

The images captured by the camera 10 are recorded on the HDD 23 oneafter another to create an image database. When the image database iscreated in the HDD 23, the user can access the image database from themonitoring device 20 to read a desired image, and can also access theimage database from an external personal computer or the like connectedto the same network N to see a desired image, because the monitoringdevice 20 is also connected to the network N.

The image monitoring system of the embodiment has the function ofdetecting a moving object from an image captured by the camera 10.Particularly, an advantage of this embodiment is that little load isapplied on the system owing to the moving-object detecting function.

The moving-object detecting function is achieved by the control of theGUI controller 102 shown in FIG. 2, which is particularly effective indetecting a moving object in the images captured by a plurality ofcameras.

FIG. 3 is a block diagram of a moving-object detecting section, denotedby 200, for use in the image monitoring system of the embodiment. Themoving-object detecting section 200 includes a decompressing section 201that decompresses an image in compressed format (for example, JPEG orMPEG format) sent from the camera 10 to bitmap data, a resolutionconverting section 202 that decreases the resolution of the decompressedbitmap data to output a low-resolution image, a positional-informationoutput section 203 that detects a moving object from the low-resolutionimage to output moving-object positional information, and an informationmerging section 204 that merges the moving-object positional informationoutput from the positional-information output section 203 with thehigh-resolution bitmap data output from the decompressing section 201.

The image in the camera 10 is sent in a specified compressed format tothe monitoring device 20 via a network. To detect a moving object in theimage sent to the monitoring device 20, the image is sent to themoving-object detecting section 200, where it is subjected to aspecified moving-object detecting process, and the detection result isoutput.

In a normal moving-object detecting process, a compressed image isdecompressed to bitmap data, in which a difference in pixel valuebetween frames is calculated to thereby detect a moving-object. However,it applies a heavy operation load and takes much time to execute themoving-object detecting process on high-resolution bitmap data and,moreover, moving-object detection for the images in multiple cameraswill apply a significant load on the system.

In this embodiment, a compressed image is decompressed into bitmap data,and then the resolution of the bitmap data is reduced to generatelow-resolution bitmap data, to which a moving-object detecting processsuch as an inter-frame differential operation is applied. This reducesthe load on the operation for detecting a moving object, allowingmoving-object detection in a short time.

It is enough for the moving-object detection only if the position of amoving-object, even with low resolution, can be sensed. Accordingly, ifthe positional information of a moving object (for example, thepositional information of a rectangular frame around the moving object)is output from the positional-information output section 203, thepositional information of the moving object can be accurately mergedwith the original bitmap data by converting the positional informationaccording to the high-resolution bitmap data.

FIG. 4 is a flowchart for the moving-object detection process which isan image monitoring program of the embodiment. First, an image streamsent from a camera is captured (step S1), which is then decompressed tobitmap data (step S2).

Next, the bitmap data is subjected to resolution conversion to decreasethe resolution (step S3). The low-resolution bitmap data is used todetect a moving object (step S4). In the moving-object detectionprocess, the positional information of a moving object in the image canbe outputted. The positional information is merged with the originalbitmap data, and is output (step S5).

To merge the positional information with the original bitmap data, thepositional information is subjected to resolution conversion reverse tothat in step S3 so that the resolution agrees with the resolution of theoriginal bitmap data. Thus, the low-resolution positional informationcan be properly agreed with the high-resolution bitmap data.

In this embodiment, the resolution of the image captured by a camera,even though it is high, is reduced in the moving-object detectingprocess. Thus hardware resources such as a CPU and a memory can be usedfor other processes without the need for using the hardware resources inthe detection process.

In the above example, moving-object detection is executed withlow-resolution bitmap data, and then it is merged with theoriginal-resolution bitmap data. However, if the resolution indisplaying images on a monitor is different from the originalresolution, the positional information obtained by moving-objectdetection may be converted to the resolution at the time of monitordisplay. When the resolution at display is equal to that atmoving-object detection such as when the window for image display issmall, the positional information of the moving object may be mergedwithout converting the resolution.

FIG. 5 is a diagram of an example of images captured by a plurality ofcameras which are displayed on a monitor. The images captured by camerasare displayed vertically and horizontally on the respective windows.FIG. 5 shows an example in which 3×3=9 windows are displayed, on whichimages by different cameras are displayed. That is, images by ninecameras can be watched at the same time. The number and layout of thewindows can be switched variously according to user selection.

There are a window switch button and a function selection button abovethe image display window. The window switch button is for selecting thecontent to be displayed on the entire screen. To display images bycameras, “Monitoring” button is selected, for basic configuration,“Configuration” button is selected, and for system setting, “System”button is selected.

The function selection button includes “Export” button for outputting animage recorded by a camera to an external recording medium (a CD-RW, aDVD-RW, a USB memory, etc.), “Full Screen” button for displaying aselected window on the entire screen, “Monitor Window” button forselecting the layout of two or more windows (3×3 or 2×2 windows), and“Sequence” button for designating to start or stop a monitor sequence inwhich the screen is switched automatically.

There are also a button for switching the mode of an image displaywindow (present image display/past image playback), a playback/recordoperation button, a camera selection button, a slide bar for volumecontrol, and a date designation box for searching for a past image underthe entire window.

There is an option window to the right of the entire window. The optionwindow can be switched among “Camera Control”, “List of RecordingCameras”, “List of Recorded Images”, “System Log”, “List of Alarm OutputStates”, “List of Sensor Input States”, “List of Moving-Object DetectingModes”, and “Manual Trigger” with a window switch button.

When “Camera Control” is selected, the window is switched to a windowfor controlling the camera functions of a designated window such as pan,tilt, zoom, focus, and brightness. When “List of Recording Cameras” isselected, a list of cameras during video shooting is displayed on theoption window. When “List of Recording Images” is selected, a list ofrecent recorded images is displayed on the option window.

When “Alarm Log” is selected, an alarm log is displayed on the optionwindow. When “System Log” is displayed, a log about system informationand error is displayed on the option window. When List of Alarm OutputStates” is selected, the present state of alarm output is displayed onthe option window. When “List of Sensor Input States” is selected, thepresent state of sensor input is displayed on the option window.

When “List of Moving-Object Detection States” is selected, informationon the present moving-object detection is displayed on the optionwindow. When “Manual Trigger” is selected, a manually started action isdisplayed on the option window.

Which image of camera is to be displayed on which window can be switchedfreely according to the instruction of the user. More specifically, whenthe user selects a desired camera with the camera selection button whiledesignating a window, the image of the selected camera is displayed onthe designated window. When the user displays “Camera Control” on theoption window while designating a window on which an image is displayed,and selects an arrow button, for example, the user can pan or tilt thecamera that is sending the image to the window, or zoom in or out theimage with a zoom button.

To see an image captured in the past, the user selects a window on whichthe present image of the camera in which the desired past image isstored, and inputs the desired past date to the date designation box. Inthis embodiment, the date designation box is displayed on the lowerright of the entire window, thus allowing date designation whilemaintaining the image display state of the window.

Here, the user can designate multiple windows corresponding to thedesired camera. Even when multiple windows are designated, one commondate setting can be accepted for the multiple windows because there isone date designation box.

In the image monitoring system of the embodiment, moving-objectdetection can be made for each of window images captured by a pluralityof cameras, with the images displayed on the respective windows, and thepositions of the detected moving objects can be each indicated by, forexample, a rectangular frame (see the broken-line frame in the drawing).When a moving object is detected, a predetermined alarm can bedisplayed.

Since images by multiple cameras can thus be displayed at the same time,simultaneous moving-object detection for multiple window images appliesa significantly heavy load. Therefore, the use of the moving-objectdetection of this embodiment allows accurate moving-object detectionwithout application of a heavy load on the system even if multiplewindows display images.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. An image monitoring system comprising: recording means for recordingan image captured by a camera via a network; control means forcontrolling the system so as to display the present image captured bythe camera or a past image recorded on the recording means on displaymeans; and moving-object detecting means for detecting a moving objectfrom the image captured by the camera; wherein the moving-objectdetecting means includes resolution conversion means for generating animage with a resolution lower than the resolution of the image capturedby the camera, positional-information output means for detecting amoving object from the image generated by the resolution conversionmeans and outputting positional information on the detected movingobject, and information merging means for merging the positionalinformation of the moving object with the image captured by the cameraon the basis of the positional information of the moving object outputby the positional-information output means.
 2. The image monitoringsystem according to claim 1, wherein the information merging meansmerges the positional information in agreement with the resolution ofthe image displayed on the display means.
 3. An image monitoring programexecuted by an image monitoring system including: recording means forrecording an image captured by a camera via a network; control means forcontrolling the system so as to display the present image captured bythe camera or a past image recorded on the recording means on displaymeans; and moving-object detecting means for detecting a moving objectfrom the image captured by the camera; wherein the moving-objectdetecting means generates an image with a resolution lower than theresolution of the image captured by the camera, detects a moving objectfrom the low-resolution image, and merges the positional information ofthe detected moving object with the image captured by the camera.
 4. Theimage monitoring program according to claim 3, wherein the positionalinformation is merged with the image in agreement with the resolution ofthe image displayed on the display means.
 5. An image monitoring systemcomprising: a recording section configured to record an image capturedby a camera via a network; a control section configured to control thesystem so as to display the present image captured by the camera or apast image recorded on the recording section on a display section; and amoving-object detecting section configured to detect a moving objectfrom the image captured by the camera; wherein the moving-objectdetecting section includes a resolution conversion section configured togenerate an image with a resolution lower than the resolution of theimage captured by the camera, a positional-information output sectionconfigured to detect a moving object from the image generated by theresolution conversion section and outputting positional information onthe detected moving object, and an information merging sectionconfigured to merge the positional information of the moving object withthe image captured by the camera on the basis of the positionalinformation of the moving object output by the positional-informationoutput section.